Where can I find "PlotView.TouchEvents.cs"?

I'm using OxyPlot-2014.1.312.1 with VS2012 Update4 and .NET Framework 4.0, WPF.
I've added a oxy:PlotView in xmal. When I debug the app on a Surface and touch on the PlotView, an exception came out and ask me to find "PlotView.TouchEvents.cs". Where can I find it?